Process for smelting ore.



F. T. SNYDER. PROCESS FOR SMELTING ORB. APPLICATION FILED JULY 1,1907.

F. T. SNYDER. PROC/'BSS FOR APPLICATION FILED JULY l, 1907,

SMELTING ORE.

Patented No? 1910.

or as e part thereof.

FR SMELTING etienne.

To all 'whom 'it muy col/wcm.:

Be it known that l. Fnunuiuon l. Snrnen, a citizen of the llnited States, residing at @tilt itjeirlsi, inthe county of Cool: and State oit lllinoim have invented a certain ne "and useful linprorement in Troc :ecs tor Smelt.n ing Ore,of u hich the l'ollowing ie u. full? clear, concise, and. o. .ct deecription.

This intention rele'tes to e procese for smeltiug ore, with eepecial .reference to the tree.. tion of steel. therefrom.

Previous attempts to produce Steel directly frein iron ore by electric euiclting ha ve niet with Serious practical diilicultiee, one ot which has been the rapid. destruction of the 'furnace walls by corroeire slugs.. li'tt'tenipts to overcome this by melting the crucible ol carbon result in impairiug' the product because the carbon combines with the mollen Inetal and producee pig iron i'netvutl ol steel.

ln accordance with the present invention, only sufficient carbon ie mined with the furnace charge to secure reduction of the metal from the ore and to produce steel; und the molten metal when produced is collected in a Crucible 4of refractory, and preferably basic, material., Such as dolomite, While the slag is counerl by a lluidcooled wall in contact therewith, which freezes the outlying portions of' the slag bath to forni a lining or container composed of solid slag. The necessary heat is produced by passing an electric current between carbon electrodes which dip into the molten slag from the top, but do net extend downward deep enough to reach and contaminate the stoel in .the Crucible. 'llWo or more 'electrodes are provided, for taking the current both into and out of the furnace through the top, in order to avoid having any Carbon in the Crucible rllhe Water-jackets protect the masonry Crucible on which they rest to a depth of several inches, and the metal level in the lCrucible is kept high enough so that the slag` cannot reach a low enough level to out through the crucible under the water-joel;- ets. The metal, however, is not allowed to accumulate in "T1 e Crucible to such an extent that it would come into contact with the Water-jackets, ae this would freeze the metal solidly upon the jackets, and result in a very Specification of etters Patent.

ent of iron ore for the direct producltjatentetl not. let/lll.

Application filed July l., 1997. Serial No. lhi.

steel by ta pnoruef.

" The described. and turiher iieaturef: hor u plrfriucr, by retereiice to the accompany I, in ulrich-- Figlure l a vertifal sectional elevation of' an electric furnace adapted to practice this` irn'ention; and litiga le a. Vertical sectional elevation at right; angles t The saule lettere of reference eamo parte in both ligures.

The liurnuce shown compri" bese 2;1 oi' refractory masonry fuite7 contained with'n und Support surrounding lnotul cul'wou al. ,iuriurnu'lting thie` Crucible baue a mrtcikjucltet foriningg a turn-ace chamber oli which the crucible is the bottoni, Tap-holes (l, (i 'l'or remet/ine; the slag are provided near the bottom of the maler-jackets., and preferably on opposite sides; thereof. These holeey are normally filled `with plugs, and only one of them is ordinarily need for tappingy thc other being provided in caee the tiret should be too dittyculty to open.

A. tap-hole 7 for removing.; metal is provided in the Wall ot the Crucible, preferably at aV point above the bottoni and dialnetrically-opposite one of the slag tape. "lhe advantage ol' thisl construction that the plug; in the metal tap-hole can bc driven out from the ineide by driving bar through, the slag tap and diagonally downwnrd acroee omcble uch ne doloef.. by u the furnace until it Strikes the plug in the as a tluxing agent at the smelting zone. The protection of the electrodes by the lime also prevents the carbon of said electrodes from unduly coinbining with the steel and impairing its quality.

lVhen the furnace is in operation, the crucible is filled nearly to the top with molten metal 8, above which is a body of molten slag 9, contained by the water-jackets 5; and the charge to be smelted is fed through the open top of the furnace to the slag bath. The furnace is heated by electric current passed between carbon electrodes l() which extend down through the top of the furnace and dip into the slag bath. The electrodes, however, are kept high enough so that they will not contact with the molten metal in the crucible. The current is taken both into and out of the fue nace by such electrodes introduced through the top of the furnace, so that the molten metal m the crucible can be maintained free from contact with carbon. Any carbon in the structure of the erueiblc would be'apt to be taken up by the steel, changing the desired composition thereof and correspondingly corroding such carbon of the crucible structure; and the use of a waterjacketed metal electrode in contact with the 'steel' would` be impracticablc because it would freeze up the metal and result in very great loss of heat,

The furnace may be started by melting pig-iron in the crueible by starting an are thereon with the electrodes, and then feeding cold slag in lumps and allowing it to melt down intil a proper quantity is provided to serve as the resistance medium. The furnace charge, consisting of ore and carbon in proper proportions to form steel, and lime as a luxing agent, is then fed into the top of the furnace around the electrodes. Preferably the Shanks of the electrodes are surrounded by lime'll to prevent them from being too quickly consumed by taking up oxygen from the ore. The lime is an oxid requiring' a much higher temperature for reduction than iron oxid, and is not itself reduced at the temperature employed, but is merely dissolved iu the slag as a fiuxing agent.

The temperature of the furnace is regulated by proportioning the furnace charge so as to produce a slag which will form at the high temperature required for iron smelting. The determination of the kind of slag to be produced is important, lbecause if the materials are so mixed as to produce a slag which forms at a low temperature, the temperature of the furnace cannot rise materially above such low point as long as any considerable portion ot' the charge remains unslnelted. Under such conditions, an increase in the strength of the electric current being applied would merely result in increasing the rate of smelting, not in increasing ,the temperature. The to be produced should preferably be made strongly basic in cha'tacter, invorderthat it may absorb the phosphorus from the ore and prevent such phosphorus from entering th steel. l Such basic slag may be produced by feeding anl excess of alkaline-oxid, such as lime, with the charge, such lim'e being preferably fed closely around the electrodes-as before described. The ore and charcoal are preferably charged in alternate layers. the last layer of charcoal 14 at the top boing always covered by a layer of ore l5, to preM vent the charcoal from being burned, as it would be if left in contact with the opelii air. f

f The o`rc is gradually reduced as it is fed downward to vard the slag. which is the hottest part of the furnace; and the metal as produced immediately sinks below the slag and collects in the refractoryfcrucible. The metal, htm'ever. is not allowed to laccumulate to such a point that it would rise into contact with the water-jackets. lVhen Ithe Crucible is full, the slag is first tapped 0H through the hole t5, after which a bar is driven through the slag tap across the furnace and through the plug which vnormally closes the metal tap, openingthe metal tap and allowing the metal to run out. lt will be noted that the/metal tap is at a point some distance above the bottoni of the cruci ble so that a considerable quantity of metal is always left in the crucible. This residual metal is useful to preserve uniformity in the product and also to maintain the heated condition of the furnace and permit a continued operation thcrctff to begin the smelt ing of the next charge. The body of metal left inthe Crucible also prevents the slag which is formed at the beginning of the next smelting operation from collecting at a low enough level to attack the lower portions of the cruciblc walls which lare not protected by the v:iter-jackets.

lt will be noted that the short-circuiting of any considerable proportion of the current through the metal 'alter-jackets is prevented, because the slag where itcomes into contact with such jackets is congealed to a solid form which is an effective insulator; the slag being an` electric conductor only when molten. lf e piece of the congealed slag lining of the water-jacket should break off, it would be in'nnediately renewed by fresh molten Islag coming into contactl therewith.

l. The process of making steel which consistal iu smelting iron ore with a minimum of carbon in an electric furnace having a ref `actory crucible surmounted by waterjacketed walls and electrodes surrounded by material adapted to flux the earthy constitulOl) ents of the ore, whereby steel low in carbon ma)4v l0 Produced and collected out of c011- tact, with carbon, and the walls of the furnace saved from corrosion in the absence of a carbon lining.

2. The process of making steel'from iron ore in an electric furnace. which consists in feeding such ore mixed with sufficient carbon to reduce such ore and provide therequired carbon contents of the steel, while preventing the absorption ot additional carbon by shielding the electrodes with lime, said linie being adz'lftld to flux the earthy constituents ot' the ore. and collecting the metal in a crucible free from carbon.

f. The process ot' operating an' electric furnace having a carbon electrode, for the smelting ot' oxid ore, which consists in feeding such or(l into the. Jfurnace and in protecting thev electrode h v surrounding said electrode with the oxid ofa metal having a temperature of redliction substantially higher than the temperature of reduction of the metal being produced.

4. The process of smelting. iron ore for the direct. production of steel, which consists in forming a furnace charge of such ore, with a quantity of carbon only slightly in excess ol the. amount. required tor reduction, smelting such charge upon a slag bath by heat dereloped by an electric current passed through said slag, Vregulating the composition ot' the furnace charge so as to produce a slag which forms at a temperature suitable for the reduction o'f the iron and formation of steel. f 'ollecting the molten metal out otl contactr with carbon in a crucible ot' basic material. while'contining said slag bath by Huid-cooled walls and thereby eongealing the outlying portions of the slag slag bath to Aform a container or lining composed of solid slag. and' collecting the molten material in a. Crucible of basic material un# derneath 4said slam 6, The process of slnelting iron ore for 'the *direct production of steel, which consists inl.

forming a furnace charge of such ore and a quantity of carbon only sufficient to reduce said ore and forni steel therefrom, smelting such furnace charge by 'heat produced 'eleotrically in the body ot' the charge, thereby forming molten slag and an underlying body of molten metal, congealing the outcrportion ofthe body of molten slag by cooling fluid to forni aso-lid slag container for said molten slag, and collecting the molten metal below the level of the slagin a Crucible of basic'lnaterial, and maintaining said material free from continuous contact with carbon: current being passed into and out -of the furnace through electrodes reaching down through the top thereof' and dipping into the molten slag, said electrodes being kept out of contact with the molten met-al in the Crucible. f

In witness whereof, I, hereunto subscribe in v name this 28th d ay of June A. D., 1907.A

FREDERICK T. SNYDER.

so'A 

